/lib/pods/SDL/Cookbook/PDL.pod

http://github.com/PerlGameDev/SDL · Unknown · 90 lines · 49 code · 41 blank · 0 comment · 0 complexity · 6143390aac0d0b22251f6f5a4f70400e MD5 · raw file

  1. =pod
  2. =head1 NAME
  3. SDL::CookBook::PDL -- CookBook for SDL + PDL
  4. PDL provides great number crunching capabilities to Perl and SDL provides game-developer quality real-time bitmapping and sound. You can use PDL and SDL ''together'' to create real-time, responsive animations and simulations. In this section we will go through the pleasures and pitfalls of working with both powerhouse libraries.
  5. =head2 CATEGORY
  6. Cookbook
  7. =head1 Creating a SDL Surface piddle
  8. PDL's core type is a piddle. Once a piddle is provided to PDL it can go do a numerous amounts of things. Please see the example in 'examples/cookbook/pdl.pl' that came with this module.
  9. =head2 Creating a simple piddle
  10. First lets get the right modules.
  11. use PDL;
  12. use SDL::Rect;
  13. use SDL::Video;
  14. use SDL::Surface;
  15. use SDL::PixelFormat;
  16. Suppose you want a surface of size (200,400) and 32 bit (RGBA).
  17. my ( $bytes_per_pixel, $width, $height ) = ( 4, 200, 400 );
  18. Define the $width, $height and $bytes_per_pixel. Your $bytes_per_pixel is the number of bits (in this case 32) divided by 8 bits per byte. Therefore for our 32 bpp we have 4 Bpp;
  19. my $piddle = zeros( byte, $bytes_per_pixel, $width, $height );
  20. Create a normal $piddle with zeros, byte format and the Bpp x width x height dimensions.
  21. my $pointer = $piddle->get_dataref();
  22. Here is where we get the actual data the piddle is pointing to. We will have SDL create a new surface from this function.
  23. my $surface = SDL::Surface->new_from( $pointer, $width, $height, 32,
  24. $width * $bytes_per_pixel );
  25. Using the same dimensions we create the surface using new_form. The width * Bpp is the scanline (pitch) of the surface in bytes.
  26. warn "Made surface of $width, $height and ". $surface->format->BytesPerPixel;
  27. return ( $piddle, $surface );
  28. Finally make sure that the surface actually has the correct dimensions we gave.
  29. B<NOTE:> $surface->format->BytesPerPixel must return 1,2,3,4. !!
  30. Now you can blit and use the surface as needed; and do PDL operations as required.
  31. =head2 Operating on the Surface safely
  32. To make sure SDL is in sync with the data. You must call SDL::Video::lock B<before> doing PDL operations on the piddle.
  33. SDL::Video::lock_surface($surface);
  34. $piddle->mslice( 'X', [ rand(400), rand(400), 1 ], [ rand(200), rand(200), 1 ] )
  35. .= pdl( rand(225), rand(225), rand(255), 255 );
  36. After that you can unlock the surface to blit.
  37. SDL::Video::unlock_surface($surface);
  38. =head2 Error due to BPP at blitting
  39. When blitting the new surface check for the return value to see if there has been a problem.
  40. my $b = SDL::Video::blit_surface(
  41. $surface, SDL::Rect->new( 0, 0, $surface->w, $surface->h ),
  42. $app, SDL::Rect->new( ( $app->w - $surface->w ) / 2, ( $app->h - $surface->h ) / 2, $app->w, $app->h )
  43. );
  44. die "Could not blit: " . SDL::get_error() if ( $b == -1 );
  45. If the error message is 'Blit combination not supported' that means that the BPP is incorrect or inconsistent with the dimensions.
  46. After that a simple update_rect will so your new surface on the screen.
  47. =head1 AUTHORS
  48. See L<SDL/AUTHORS>.
  49. =cut